A Tbc1d1Ser231Ala-knockin mutation partially impairs AICAR- but not exercise-induced muscle glucose uptake in mice

Qiaoli Chen, Bingxian Xie, Sangsang Zhu, Ping Rong, Yang Sheng, Serge Ducommun, Liang Chen, Chao Quan, Min Li, Kei Sakamoto, Carol MacKintosh, Shuai Chen (Lead / Corresponding author), Hong Yu Wang (Lead / Corresponding author)

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Abstract

Aims/hypothesis: TBC1D1 (tre-2/USP6, BUB2, cdc16 domain family member 1) is a Rab GTPase-activating protein (RabGAP) that has been implicated in regulating GLUT4 trafficking. TBC1D1 can be phosphorylated by the AMP-activated protein kinase (AMPK) on Ser(231), which consequently interacts with 14-3-3 proteins. Given the key role for AMPK in regulating insulin-independent muscle glucose uptake, we hypothesised that TBC1D1-Ser(231) phosphorylation and/or 14-3-3 binding may mediate AMPK-governed glucose homeostasis.

Methods: Whole-body glucose homeostasis and muscle glucose uptake were assayed in mice bearing a Tbc1d1 (Ser231Ala)-knockin mutation or harbouring skeletal muscle-specific Ampkα1/α2 (also known as Prkaa1/2) double-knockout mutations in response to an AMPK-activating agent, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR). Exercise-induced muscle glucose uptake and exercise capacity were also determined in the Tbc1d1 (Ser231Ala)-knockin mice.

Results: Skeletal muscle-specific deletion of Ampkα1/a2 in mice prevented AICAR-induced hypoglycaemia and muscle glucose uptake. The Tbc1d1 (Ser231Ala)-knockin mutation also attenuated the glucose-lowering effect of AICAR in mice. Glucose uptake and cell surface GLUT4 content were significantly lower in muscle isolated from the Tbc1d1 (Ser231Ala)-knockin mice upon stimulation with a submaximal dose of AICAR. However, this Tbc1d1 (Ser231Ala)-knockin mutation neither impaired exercise-induced muscle glucose uptake nor affected exercise capacity in mice.

Conclusions/interpretation: TBC1D1-Ser(231) phosphorylation and/or 14-3-3 binding partially mediates AMPK-governed glucose homeostasis and muscle glucose uptake in a context-dependent manner.

Original languageEnglish
Pages (from-to)336-345
Number of pages10
JournalDiabetologia
Volume60
Issue number2
Early online date8 Nov 2016
DOIs
Publication statusPublished - Feb 2017

Keywords

  • 14-3-3
  • AMPK
  • Glucose uptake
  • Phosphorylation
  • TBC1D1

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